1. Field of the Invention
The present invention generally relates to Power over Ethernet (PoE) devices, and more specifically to midspans for PoE with inband power management.
2. Related Art
Ethernet communications provide high speed data communications over a communications link between two communications nodes that operates according the IEEE 802 Ethernet Standard. The communications medium between the two nodes can be twisted pair wires for Ethernet, or other types communications medium that are appropriate. Power over Ethernet (PoE) communication systems provide power and data communications over a common communications link. More specifically, a power source device (PSE) connected to the physical layer of the first node of the communications link provides DC power (for example, 48 volts DC) to a powered device (PD) at the second node of the communications link. The DC power is transmitted simultaneously over the same communications medium with the high speed data from one node to the other node.
Example PD devices that utilize PoE include Internet Protocol (IP) phones, wireless access points, etc. The PSE device is often a data switch having has least two rows of data ports, where a data port in the input row of data ports can to be switched to any one of the data ports in the output row of data ports. Each data port typically includes a serial-to-parallel (i.e. SERDES) transceiver, and/or a PHY device, to support high speed serial data transport. Herein, data ports and their corresponding links can be interchangeably referred to as data channels, communication links, data links, etc, for ease of discussion.
Despite the advantages of PoE, many existing communication links do not utilize PoE and transfer only pure data. Accordingly, some existing switches are data-only switches that do not support power transfer, i.e., they are non-PoE switches. However, in some configurations, these data-only switches may need to communicate with PD devices on a number of their data ports. In this scenario, a midspan switch is connected between the data-only switch and the PD devices in order to inject the DC power to operate the PD devices.
A midspan controller, which is external to the midspan, manages the DC power injection by the midspan using management traffic that is communicated with the data-only switch. Current midspans utilize a separate management port to receive and process the management traffic that passes from the switch through the midspan to the external midspan controller, and vice versa. This separate management port on the midspan necessitates that the data-only switch also dedicate a data port to management traffic, which is an inefficient use of data ports on both the data-only switch and the midspan.
What is needed is a midspan configuration that does not require a dedicated port to be used for management traffic, so as to improve the integrated circuit die area efficiency for both the switch and the midspan.